The technical field of this disclosure is disc brakes for vehicles and particularly a torque sensor for a disc brake mounting bracket.
Current design practice with regard to hydraulic brake apply systems is to measure brake torque by using a hydraulic pressure transducer and wheel speed sensor to estimate wheel brake torque. In addition to a measured velocity of a rotor in a brake system, torque values are used in Antilock Brake Systems (ABS) in an algorithm to control operation of the braking system. The accuracy of the actual brake torque is critical to intelligent brake control of ABS or other braking systems. Brake pressure or normal loading to the rotor, however, cannot be accurately used to measure torque due to the variation of coefficient of friction produced between various brake pads (0.1 dry hard to 0.4 wet soft) and rotor cheeks.
Therefore, it would be beneficial to provide an apparatus for accurately measuring torque in a brake system.
One aspect of the present invention provides a mounting bracket apparatus for a disc brake of a vehicle including a bracket capable of being secured to a non-rotatable part of a vehicle, the bracket including first and second caliper bracket abutments and a cross member extending in the direction of the rotational axis of the disc, the cross member joining the first and second caliper bracket abutments at respective first and second corner-shaped portions and a force sensor located adjacent to the first corner-shaped portion of the bracket adapted to sense strain in the first corner-shaped portion.
Other aspects include a mounting bracket apparatus wherein the force sensor can be a strain gage. The bracket can include, in the first corner-shaped portion, a void. The void can be a cylindrical void or a rectangular void. The first corner-shaped portion can include a tapered cross-sectional portion. The corner-shaped portion can taper toward the outer edge of the corner-shaped portion. The tapered cross-sectional portion can include a void. The void may be a cylindrical or rectangular void.
In other aspects of the invention the force sensor can include a load cell formed integrally into the tapered portion of the first corner-shaped portion. The sensor can be attached to an outer surface of the bracket across the first corner-shaped portion. The force sensor can be attached in a slot in the bracket across the first corner-shaped portion. The force sensor can be attached to a sensor bracket across the first corner-shaped portion. The sensor bracket can include a first end attached to the first caliper bracket abutment and a second end attached to the cross-member. The sensor bracket can taper towards an outer edge of a sensor-mounting portion of the sensor bracket. The sensor bracket can include at least one void. The sensor bracket can include a plurality of voids. The plurality of voids causes amplification of the strain in the first bracket abutment. The mounting bracket apparatus includes a first caliper bracket abutment adapted to receive a brake force.
Another aspect of the present invention provides a method of measuring torque in a disc brake mounting bracket including applying a brake force to the disc brake mounting bracket, amplifying strain at an outer portion of the disc brake mounting bracket, sensing strain adjacent the outer portion of the disc brake mounting bracket and generating a signal to send to a disc brake control system. In other aspects of the method of the invention the outer portion can be a predetermined tapered portion of the bracket and the outer portion can include a void formed therein.
The foregoing and other features and advantages of the invention will become further apparent from the following detailed description of the presently preferred embodiments, read in conjunction with the accompanying drawings. The detailed description and drawings are merely illustrative of the invention rather than limiting, the scope of the invention being defined by the appended claims and equivalents thereof.